Now you're just changing the definition to try to win an argument. An xrisk is typically defined as one that, in and of itself, would result in the complete extinction of a species. If A causes a situation that prevents us from dealing with B when it finally arrives the xrisk is B, not A. Otherwise we'd be talking about poverty and political resource allocation as critical xrisks, and the term would lose all meaning.
I'm not going to get into an extended debate about energy resources, since that would be wildly off-topic. But for the record I think you've bought into a line of political propaganda that has little relation to reality - there's a large body of evidence that we're nowhere near running out of fossil fuels, and the energy industry experts whose livelihoods rely on making correct predictions mostly seem to be lined up on the side of expecting abundance rather than scarcity. I don't expect you to agree, but anyone who's curious should be able to find both sides of this argument with a little googling.
Now you're just changing the definition to try to win an argument.
So Nick Bostrom, who seems to be one of the major thinkers about existential risk seems to think that this justifies being discussed in the context of existential risk http://www.nickbostrom.com/existential/risks.html . In 5.1 of that link he writes:
...The natural resources needed to sustain a high-tech civilization are being used up. If some other cataclysm destroys the technology we have, it may not be possible to climb back up to present levels if natural conditions are less favorable
The FHI's mini advent calendar: counting down through the big five existential risks. The first one is an old favourite, forgotten but not gone: nuclear war.
Nuclear War
Current understanding: medium-high
Most worrying aspect: the missiles and bombs are already out there
It was a great fear during the fifties and sixties; but the weapons that could destroy our species lie dormant, not destroyed.
But nuclear weapons still remain the easiest method for our species to destroy itself. Recent modelling have confirmed the old idea of nuclear winter: soot rising from burning human cities destroyed by nuclear weapons could envelop the world in a dark cloud, disrupting agriculture and the food supplies, and causing mass starvation and death far beyond the areas directly hit. And a creeping proliferation has spread these weapons to smaller states in unstable areas of the world, increasing the probability that nuclear weapons could get used, leading to potential escalation. The risks are not new, and several times (the Cuban missile crisis, the Petrov incident) our species has been saved from annihilation by the slimmest of margins. And yet the risk seems to have slipped off the radar for many governments: emergency food and fuel reserves are diminishing, and we have few “refuges” designed to ensure that the human species could endure a major nuclear conflict.